Wireless mobile communication technology uses various standards and protocols to transmit data between a network node (e.g., a transmission station) and a wireless device (e.g., a mobile device). Some wireless devices communicate using orthogonal frequency-division multiple access (OFDMA) in a downlink (DL) transmission and single-carrier frequency-division multiple access (SC-FDMA) in an uplink (UL) transmission. Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include the third-generation partnership project (3GPP) long-term evolution (LTE), the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m), which is commonly known to industry groups as WiMAX (Worldwide interoperability for Microwave Access), and the IEEE 802.11 standard, which is commonly known to industry groups as WiFi.
In 3GPP radio access network (RAN) LTE systems, the network node can be an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs). The network node can communicate with the wireless device; a user equipment (UE) is one example of such a wireless device. The downlink (DL) transmission can be a communication from the network node (e.g., eNodeB) to the wireless device (e.g., UE), and the uplink (UL) transmission can be a communication from the wireless device to the network node. The geographical area wherein wireless devices are served by the network node can be referred to as a cell.
In LTE systems, data can be transmitted from the eNodeB to the UE via a physical downlink shared channel (PDSCH). A physical uplink control channel (PUCCH) can be used to acknowledge that data was received. Downlink and uplink channels or transmissions can use time-division duplexing (TDD) or frequency-division duplexing (FDD).
A D2D communication is a direct communication between two devices, such as two user equipments (UEs). The two devices (e.g., LTE-based devices) can communicate directly with one another when the two devices are in relatively close proximity. D2D communications may be assisted by a cellular system such as LTE or may not use the cellular network infrastructure at all.
Reference will now be made to the exemplary embodiments illustrated and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of is thereby intended.